The supply of gunpowder haunted George Washington and the Continental Congress throughout the entire Revolutionary War. The vast quantity of powder came from sources overseas , around 90% from French Colonies in the West Indies. The other 10% was produced domestically. With dwindling powder supplies and only three powder mills in operation in all of the colonies, Washington’s army around Cambridge was is serious danger at the start of the war.
The time and place of the invention of black powder or gunpowder is not entirely clear among scholars. Many claim it was invented in China in the 9th century, the first passage is in a Taoist dated in the mid 800’s. It is believed that the first reference to gunpowder in warfare was first used in China in 919 to ignite Greek Fire. An early formula of Chinese black powder was published in the Wujing Zongyao in 1044 AD. Roger Bacon, in his De Secreatis Operibus Artis et Naturae in 1248 gives the formula for gunpowder as described in an acronym. Later in his Opus Majus of 1268, saltpeter is discussed in the making of gunpowder. Additional scholars credit Marceus Graecus, a pseudonym of an unknown medieval alchemist, whose treatise in 1250 contains a formula for strong gunpowder. And lastly, a German Franciscan Monk, Berthold Schwarts, in 1380, gave a detailed account of the use of black powder in guns.
Gunpowder is a mixture. In other words, the ingredients do not bond on an atomic or molecular level and must be combined. Four ingredients are used in the manufacture of black powder: saltpeter (or nitrates), sulfur (or brimstone), charcoal from coal and water. Basically equal parts of the first three are combined however more saltpeter will produce powder for muskets and even more for pistols. Sulfur and the charcoal acted as the fuel and saltpeter as the oxidizer. Because of the amount of heat and gas volume it generates, this mixture has been used as a propellant.
The process combining these materials used powder mills driven by wind or water. They utilized large wheels or rollers for grinding, presses, tumbling barrels and sieves for compacting, granulating and grading the powder. Because of the danger of spark igniting the powder, Powder mills were usually situated far from habitation and surrounded by a high dirt berm. One or more walls of the mill were built purposely weak so the force would be adverted through these walls leading out onto a river or field in case of an explosion,
Basically, the ingredients were moistened to avoid sparks and then ground beneath large stones similar to grinding flour. They were then moistened into a paste and pushed through a sieve in a process known as ‘corning the powder’. It produced small grains of which the size and shape determined the quality of the powder.
Washington knew the hopes of the American cause rested on imported gunpowder. Swiss and French powder were the most sought after, especially by the riflemen who artfully measured their black powder down their gun’s muzzles with powder horns. The Continental Army had about 80,000 pounds of powder on hand in the Spring of 1775, but by December of that same year, almost every ounce of that had been used, according to Washington, in a wasteful manner. He also attributed the shortage to damage the powder sustained from heavy rain when the troops were sheltered in poor tents.
That same year, 1775, the Second Congress authorized the purchase of 500 tons of powder. The Committee of Secret Correspondence was told to find it however it could. Members immediately began to explore clandestine shipments from overseas governments, refitted their own ships to run British blockades, armed vessels to pirate British supply ships, and revitalized the local powder mills.
Most powder was obtained from the West Indies where large quantities were available. Between the sixth and fourteenth of May, 1776, fourteen ships arrived from Martinique bringing 100,000 hundredweight of gunpowder. In mid-July of that year, twelve more ships arrived each carrying 10,000 hundredweight of powder. The Secret Committee sent ships to Marseilles, which not only brought in an average of 10 tons of powder per voyage, but much needed muskets and lead as well.
In October of 1775, General Washington had equipped two armed ships, the Lynch and the Franklin. He ordered their captains to seek and intercept British supply ships, particularly those carrying munitions. He offered the captain and crew one-third of the value of any prize taken, including the ship. It became known as “Washington’s fleet” and the small fleet of armed vessels accounted well for itself, even after Congress established a naval force.
Washington and Congress appealed to the colonies to increase domestic powder manufacturing which had been, nonexistent at the start of the war other than three small mills: Frankford Powder Mill, which was the largest just outside Philadelphia and owned by Oswald Eve and his son; Pickeland Powder Mill, run by Peter De Haven, about 30 miles northwest of Philadelphia; and a mill outside Morristown, NJ owned by Jacob Ford Jr. A typical mill consisted of a dam, mill race, powder mill, graining mill, saltpeter house, drying houses, powder magazine, and the powder master’s residence. To stimulate additional mill construction, Congress authorized payment of all domestic black powder at eight dollars per hundredweight. Several more mills were opened in New York, Connecticut at Canton, and Massachusetts. In fact, Paul Revere studied the Frankford Mill manufacturing procedure to set the pattern and establish mills in New England.
If gunpowder was to be made in America, it needed a strong supply of saltpeter, and America, like England, had a severe shortage of natural saltpeter or nitrates. First off, all tobacco colonies were made aware that the surface of the earth in their tobacco warehouses and yards was strongly impregnated with nitrates and plantation owners were requested to erect saltpeter factories on rivers near their warehouses. The Second Continental Congress even printed and distributed a pamphlet on how to make saltpeter and was willing to buy up all saltpeter produced at half a dollar per pound. The pamphlet recommended: “[that] vegetable and animal refuse containing nitrogen [were collected], the sweepings of slaughterhouses, weeds, etc., were collected into heaps in a shed or house where they were protected from the rain, and mixed with limestone, old mortar and ashes. The heaps were moistened from time to time with runnings from stables and other urine. When decomposition was complete, the heaps were leached with water, the liquor evaporated, and the saltpeter recrystallized.”
In all, domestic gunpowder milling only produced 100,000 pounds of powder from 1775 through 1777, but it helped the American forces sustain their army at a critical time for survival. Things improved dramatically as the French ships supplied the rebel forces beginning in mid 1776 shipping in over one million pounds of powder helping to ensure the continuation of the American struggle for independence.
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Bacon, Roger. Epistola de Secretis Operibus Naturae et de Nullitate Magiae, Translation and Quotes in Atlantic Monthly, Vol. 6. No. 38 Deceber 1860.
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Davis, Tenney L. The Chemistry of Powder and Explosives. 1943 Reprint 1984 Angriff, CA.
Partington, James Riddick & Hall, Bert S. A History of Greek Fire and Gunpowder. 1999 John Hopkins University Press, Baltimore
Risch, Erna. Supplying Washington’s Army. 1979 Center of Military History, U.S. Army, Washington D.C
Van Gelder, Arthur Pine & Schlatter, Hugo. History of the Explosives Industry in America. 1927 Columbia University Press, New York.